Controlling laser-induced magnetization reversal dynamics in a rare-earth iron garnet across the magnetization compensation point

TLDR

Ultrafast magnetization control with femtosecond lasers is crucial for physics and technology, and the observed dynamics are explained by a reversal process across the compensation temperature T_M. The study investigates laser‑induced ultrafast magnetization dynamics in a rare‑earth iron garnet across a wide temperature range that includes the compensation point T_M. The authors used femtosecond laser pulses to probe the magnetization dynamics of the garnet over a broad temperature range spanning T_M. The study shows that phonon‑assisted d‑d transitions generate large‑amplitude magnetization dynamics just below T_M, and that both the speed and amplitude of these dynamics can be tuned by adjusting laser energy density or external magnetic field strength.

Abstract

The ultrafast manipulation of the magnetization using femtosecond laser pulses is of utmost importance for both fundamental physics and technological applications. Here, the authors investigated the laser-induced ultrafast magnetization dynamics in a rare-earth iron garnet over a broad temperature range including the magnetization compensation point T${}_{\mathrm{M}}$. They find that the heat energy resulting from exciting the phonon-assisted $d$-$d$ transitions induces large-amplitude magnetization dynamics at temperatures slightly below T${}_{\mathrm{M}}$. They also demonstrate that the speed and the amplitude of the magnetization dynamics can be controlled by tuning either the laser energy density or the amplitude of the external magnetic field. The obtained results are explained by a magnetization reversal process across T${}_{\mathrm{M}}$.